Heat Exchanger for a Condenser Unit which Eliminate Corner and Concentric Eddies for High Energy Efficiency

ABSTRACT

A heat exchanger coil for a condenser unit which eliminate corner and concentric eddies for high energy efficiency includes a continuous curvature of an oval shape profile across a cross sectional view. The heat exchanger coil includes a circular section, a first planar section, a second planar section, and a coil opening as the first planar section and the second planar section are adjacently connected and tangentially positioned with the circular section. The configuration between the circular section, the first planar section, and the second planar section delineate the continuous curvature of an oval shape and the coil opening. The heat exchanger coil is internally placed within a cabinet assembly and connected with other associated components of an outdoor condensing unit or outdoor unit so that the heat exchanger coil is able to eliminate corner and concentric eddies that are generally present within rectangular and circular shaped heat exchangers.

The current application claims a priority to the U.S. Provisional Patent application Ser. No. 62/054,576 filed on Sep. 24, 2014.

FIELD OF THE INVENTION

The present invention relates generally to a heating ventilation and air conditioning (HVAC) heat exchanger that eliminates corner and concentric eddies for high energy efficiency. The heat exchanger generally has applications in HVAC systems, and relates more particularly to condensing or outdoor unit of a central air conditioner or heat pump, and like systems.

BACKGROUND OF THE INVENTION

Energy conservation and energy efficiency both mean using less energy. These terms are often used interchangeably; however, they have important differences. Energy conservation refers to any behavior that result in not using energy at all, such as turning off the lights when not needed. Energy efficiency, however, is a technological approach to using less energy or using energy more effectively in order to perform the same function and deliver the same result.

In HVAC systems, energy efficiency of air conditioners measures the difference between how much energy is used to provide the same level of comfort by the same type of products and is often referred to as Energy Efficiency Ratio (EER) defined as the product's cooling output in BTUs per hour divided by its consumption of electric energy measured in watts. In HVAC industry, Seasonal Energy Efficiency Ratio (SEER) is often preferred to describe energy efficiency of air conditioners. The SEER is defined as the cooling output during a typical cooling season divided by the total electric energy input during the same period.

In HVAC industry, several technological methods had been used to improve the energy efficiency of air conditioning or heat pump systems, such as, developing more efficient fans, fan motors, compressors and heat exchangers. One object of the present invention is to improve on the existing heat exchangers, in particular the condensing units of central air conditioners and outdoor (evaporator) units of central heat pump split systems, for higher energy efficiency.

Most condenser coils of central air conditioning and outdoor units of central heat pump split systems on the market today have rectangular shape, few are circular and none are oval or a non-circular shape of continuous curvature of the present invention. Rectangular condensing coils are subjected to corner flow singularities and eddies resulting in energy dissipation in form of heat. The circular condensing coils experience concentric flow recirculation or eddy with occurrence of non-recoverable energy loss also in form of heat. However, the dissipated or lost energy must be supplied if air is to be maintained in motion, in the same way, as energy must be provided to overcome friction. The supply of more energy to accomplish the designed performance of a heat exchanger or condensing unit results in a decrease in the efficiency of the unit.

It is an object of the present invention to provide a heat exchanger condensing coil with a non-circular shape of continuous curvature which avoids the problems of corner flow singularities and eddies, and the concentric flow recirculation or eddies to attain higher energy efficiency due to energy savings as a result of reduction in fan power as compared to the condensing unit with rectangular or circular condensing coils.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the present invention within a condensing unit.

FIG. 2 is a perspective view of the present invention shown within an exploded view of a condensing unit.

FIG. 3 is a perspective view of the present invention.

FIG. 4 is another perspective view of the present invention, without the plurality of cooling fins.

FIG. 5 is a top view of the present invention, showing the angle between the free edge of the first planar section and the free edge of the second planar section.

FIG. 6 is a top view of the present invention, showing that the chord length is greater than the radius of the circular section.

FIG. 7 is a top view of the present invention, showing the ratio for the chord length to the length from the free edge to the fixed edge of the first planar section and the ratio for the chord length to the length from the free edge to the fixed edge of the second planar section.

FIG. 8 is a top view of the present invention depicting polar and Cartesian coordinates and the interlocking triangular and circular regions for the numerical simulation.

FIG. 9 is an illustration showing the numerical flow distributions or patterns for the rectangular heat exchanger and the corner flow singularities.

FIG. 10 is an illustration showing the interferogram flow distributions or patterns for the rectangular heat exchanger and the corner flow singularities.

FIG. 11 is an illustration showing the numerical flow distributions or patterns for the circular heat exchanger and the concentric flow recirculation.

FIG. 12 is an illustration showing the interferogram flow distributions or patterns for the circular heat exchanger and the concentric flow recirculation.

FIG. 13 is an illustration showing the numerical flow distributions or patterns for the present invention.

FIG. 14 is an illustration showing the interferogram flow distributions or patterns for the present invention.

DETAIL DESCRIPTIONS OF THE INVENTION

All illustrations of the drawings are for the purpose of describing selected versions of the present invention and are not intended to limit the scope of the present invention.

The present invention, a heat exchanger coil 1, is suitable for use as a component of a heating, ventilation and air conditioning (HVAC) system with specific application in a condenser unit or an outdoor unit of a central air conditioner or heat pump. However, the scope of the present invention is not limited by the aforementioned applications. The present invention, as well as the associated principles, may also apply to other HVAC system. The present invention overcomes many of the shortcomings of the conventional rectangular or circular heat exchangers of central air conditioning and heat pump systems. For example, the present invention experiences no corner or concentric flow eddies as compared to a rectangular heat exchanger with substantial corner flow singularities and eddies or a circular heat exchanger with significant concentric flow recirculation or eddies. The present invention is better understood with reference to the preferred embodiment to be provided hereinafter as the preferred embodiment shows the non-circular shape with continuous curvature that can be an oval or similar shaped profiles with no corners.

In reference to FIG. 1 and FIG. 4, the heat exchanger coil 1 comprises a circular section 2, a first planar section 3, a second planar section 4, and a coil opening 5 so that the heat exchanger coil 1 is able to delineate the continuous curvature of an oval shape. More specifically, a path followed by a cross section of the heat exchanger coil 1 illustrates the continuous curvature of an oval shape as shown in FIG. 5-8. The circular section 2, which primarily delineates the shape of the heat exchanger coil 1, comprises a first arc edge 21 and a second arc edge 22. The first planar section 3 and the second planar section 4 each comprise a fixed edge 31 and a free edge 32 as the first planar section 3 and the second planar section 4 is oppositely positioned of each other along the circular section 2. In reference to FIG. 5-7, the first arc edge 21 and the second arc edge 22 are offset from each other along the circular section 2 as each edge defines an endpoint of the circular section 2. The fixed edge 31 of the first planar section 3 is adjacently connected with the first arc edge 21 in such a way that the first planar section 3 is tangentially positioned with the circular section 2. Similarly, the fixed edge 31 of the second planar section 4 is adjacently connected with the second arc edge 22 in such a way that the second planar section 4 is tangentially positioned with the circular section 2. The free edge 32 of the first planar section 3 is positioned opposite of the fixed edge 31 of the first planar section 3 while the free edge 32 of the second planar section 4 is positioned opposite of the fixed edge 31 of the second planar section 4. The positioning of the free edge 32 of the first planar section 3 and the free edge 32 of the second planar section 4 delineate the coil opening 5. The coil opening 5 is able to provide access area for other associated components of the heat exchanger coil 1 that may be positioned on or within the heat exchanger coil 1.

In reference to FIG. 5, an angle 24 positioned between the free edge 32 of the first planar section 3 and the free edge 32 of the second planar section 4 is an acute angle so that the heat exchanger coil 1 can be operated at the maximum efficiency. More specifically, the acute angle between the free edge 32 of the first planar section 3 and the free edge 32 of the second planar section 4 is preferably about 77 degrees as a reflex angle of the acute angle measured to be about 283 degrees. In reference to FIG. 6-7, a chord length 25 that is measured between the first arc edge 21 and the second arc edge 22 is greater than a radius 23 of the circular section 2. More specifically, a ratio for the chord length 25 to the radius 23 of the circular section 2 is about 1.25 to 1. Additionally, a ratio between the chord length 25 and a length 16 from the free edge 32 to the fixed edge 31 of the first planar section 3 is about 3.4 to 1. Furthermore, a ratio between the chord length 25 and a length 17 from the free edge 32 to the fixed edge 31 of the second planar section 4 is about 3.4 to 1.

In reference to FIG. 2 and FIG. 3, the heat exchanger coil 1 further comprises a plurality of cooling fins 6, a plurality of condenser tubes 7, a vapor intake manifold 8, and a liquid discharge manifold 9. More specifically, the plurality of cooling fins 6 is vertically extended from the free edge 32 of the first planar section 3 to the free edge 32 of the second planar section 4. The plurality of condenser tubes 7 horizontally traverses through the plurality of cooling fins 6 from the free edge 32 of the first planar section 3 to the free edge 32 of the second planar section 4. As result, the plurality of cooling fins 6 and the plurality of condenser tubes 7 are perpendicularly oriented with the each other so that the temperature of the refrigerant that circulates within the plurality of condenser tubes 7 can be altered according to a condensing unit or outdoor unit specification. Both the vapor intake manifold 8 and the liquid discharge manifold 9 are in fluid communication with the plurality of condenser tubes 7 so that the condensing unit or outdoor unit can be in fluid communication with a refrigerant vapor suction line and a refrigerant subcooled liquid line which in turn are in fluid communication with an inside air handler unit.

In reference to FIG. 1-2, the heat exchanger coil 1 associates with a base pan 12, a top cover 13, a protective grill 14, and a back panel 15. The base pan 12, the top cover 13, the protective grill 14, and the back panel 15 jointly function as the cabinet assembly for the heat exchanger coil 1. The cabinet assembly houses and protects a compressor unit, a fan and motor assembly, and control units of the condensing unit or outdoor unit can be protected within the cabinet assembly. In reference to FIG. 2, the base pan 12 is adjacently positioned around a bottom edge 10 of the heat exchanger coil 1, while the top cover 13 is adjacently positioned around a top edge 11 of the heat exchanger coil 1, opposite of the base pan 12. The base pan 12 provides a foundation for the heat exchanger coil 1, the compressor unit, and other essential components so that the condensing unit or outdoor unit can be assembled together. The top cover 13 provides the necessary surface to mount the fan and motor assembly as well as protect the heat exchanger coil 1 from environmental elements that can negatively affect the efficiency of the heat exchanger coil 1. The top cover 13 comprises a fan guard that is concentrically positioned on the top cover 13. The fan guard offers protection against the fan blades and allows the air to escape from the condensing unit or outdoor unit after the air is drawn through the heat exchanger coil 1. The protective grill 14 is concentrically positioned around the heat exchanger coil 1 as the base pan 12 and the top cover 13 are mounted to each other through the protective grill 14. The protective grill 14 functions similar to the top cover 13 and protects the heat exchanger coil 1 from environmental elements that can damage or hinder the efficiency of the heat exchanger coil 1. The back panel 15 is adjacently positioned with the coil opening 5 and mounted to the base pan 12 and the top cover 13. The back panel 15, which completes the cabinet assembly, functions as an access door within the condensing unit or outdoor unit so that the internal components can be accessed without having to dissemble the condensing unit or outdoor unit completely. The base pan 12, the top cover 13, and the protective grill 14 are shaped and manufactured for efficient internal placement of the heat exchanger coil 1 so that the cabinet assembly does not interrupt the non-circular continuous curvature of an oval shape profile of the heat exchanger coil 1. For example, the base pan 12, the top cover 13, and the protective grill 14 are preferably shaped into the same oval shape of the heat exchanger coil 1 so that the cabinet assembly can be efficiently placed around the present invention.

In reference to FIG. 8, the present invention is able to increase the efficiency thereby eliminating corner flow singularities and eddies associated with rectangular heat exchangers; and of a non-circular shape of continuous curvature of an oval shape that induces non-axisymmetric flow to suppress concentric eddies commonly present in circular heat exchangers. To achieve this, the present invention utilizes a finite difference numerical method and a laser interferometer experimental technique to study the flow distributions or patterns of the heat exchanger coil 1 of non-circular shape for the continuous curvature of an oval shape while varying its parameters and profiles until concentric eddies disappear. The finite difference numerical method used herein requires that the heat exchanger coil 1, which can be made by bending a coil slab, be portioned into a first domain and a second domain. The first domain is a circular domain has polar coordinates and the second domain is an isosceles triangular domain with a vertex and two congruent legs and consisting of Cartesian coordinates. A dividing line, which is the chord length 25 that extends from the first arc edge 21 to the second arc edge 22, is an imaginary interface between the polar and Cartesian coordinates. Other numerical methods which could yield similar results as the finite difference are the finite element numerical method and the conformal mapping technique. These methods and techniques avoid the use of mixed coordinates (polar and Cartesian), but are more applicable to civil or structural engineering analysis. The governing differential equations of the flow in both the Cartesian coordinates and polar coordinates are developed and transformed below into stream functions and voracity formulations to produce theoretical flow visualization in the present invention.

Cartesian Coordinate

Stream function equation:

${\frac{\partial^{2}\psi}{\partial x^{*2}} + \frac{\partial^{2}\psi}{\partial y^{*2}}} = {- \omega}$

Vorticity equation:

${{\frac{\partial\psi}{\partial y^{*}}\frac{\partial\omega}{\partial x^{*}}} - {\frac{\partial\psi}{\partial x^{*}}\frac{\partial\omega}{\partial y^{*}}}} = {{\frac{Gr}{{Re}_{w}^{2}}\left( {{\sin \; \alpha \frac{\partial\theta}{\partial x^{2}}} + {\cos \; \alpha \frac{\partial\theta}{\partial y^{2}}}} \right)} + {\frac{1}{{Re}_{w}}\left( {\frac{\partial^{2}\psi}{\partial x^{*2}} + \frac{\partial^{2}\psi}{\partial y^{*2}}} \right)}}$

Polar coordinates

Stream function equation:

${\frac{\partial^{2}\psi}{\partial r^{2}} + {\frac{1}{r}\frac{\partial\psi}{\partial r}} + {\frac{1}{r^{2}}\frac{\partial^{2}\psi}{\partial\theta^{2}}}} = {- \omega}$

Vorticity equation:

${{v_{r}\frac{\partial\omega}{\partial r}} + {\frac{v_{\theta}}{r}\frac{\partial\omega}{\partial\theta}}} = {{\frac{Gr}{{Re}_{w}^{2}}\left\lbrack {{{- \frac{\partial\theta}{\partial r}}{\sin \left( {\theta + \alpha} \right)}} - {\frac{1}{r}\frac{\partial\theta}{\partial\theta}{\cos \left( {\theta + \alpha} \right)}}} \right\rbrack} + {\frac{1}{{Re}_{w}}\left( {\frac{\partial^{2}\omega}{\partial r^{2}} + {\frac{1}{r}\frac{\partial\omega}{\partial r}} + {\frac{1}{r^{2}}\frac{\partial^{2}\omega}{\partial\theta^{2}}}} \right)}}$ $\mspace{20mu} {{Where},\mspace{20mu} {\phi = \frac{k}{\rho \; c_{\rho}}}}$ $\mspace{20mu} {{Gr}_{w} = \frac{g\; \beta \; {w^{3}\left( {T_{w} - T_{\infty}} \right)}}{v^{2}}}$ $\mspace{20mu} {{Re}_{w} = \frac{u_{m} \cdot w}{v}}$ $\mspace{20mu} {\theta = \frac{T - T_{\infty}}{T_{w} - T_{\infty}}}$ $\mspace{20mu} {\Pr = \frac{v}{\phi}}$ $\mspace{20mu} {u^{*} = \frac{u}{u_{m}}}$ $\mspace{20mu} {v^{*} = \frac{v}{u_{m}}}$ $\mspace{20mu} {u^{*} = \frac{\partial\psi}{\partial y^{*}}}$ $\mspace{20mu} {v^{*} = {- \frac{\partial\psi}{\partial x^{*}}}}$ $\mspace{20mu} {\omega = {\frac{\partial v^{*}}{\partial x^{*}} - \frac{\partial u^{*}}{\partial y^{*}}}}$ $\mspace{20mu} {x^{*} = \frac{x}{W}}$ $\mspace{20mu} {y^{*} = \frac{y}{W}}$

x^(*), y^(*) are non-dimensional Cartesian coordinates; r, θ are non-dimensional polar coordinates; u^(*), v^(*) are non-dimensional velocity in Cartesian coordinates; v_(r), v_(θ)are non-dimensional velocity in polar coordinates; α=0 and T=Temperature

The stream function vorticity formulations discussed above are discretized and numerically solved at nodal points of the Cartesian and polar mesh systems. Since the polar and Cartesian coordinates share a common boundary at their interface it is required to interlock and overlap the two coordinates in order to obtain solution at the interface. This is accomplished by completing the circular domain which overlaps and interlocks with the isosceles triangular domain. The area bounded by the circular domain is referred to as a region B while the area bounded by the isosceles triangular domain is referred as a region A. The numerical solution then proceeds as follows:

Some arbitrary values of the stream function and vorticity are first assigned along the interface of the polar and Cartesian coordinates. These arbitrary values are chosen randomly and may consist of zeros since they are used only for the first cycle of iterations and are updated later. The solution procedure then begins with the region A. Some numbers of iterations are performed in the region A by using the Cartesian coordinates and a successive over-relaxation (sometimes under-relaxation) procedure. The results of these iterations are then used to establish false nodal values along the overlapping boundary which completes the region B into a full circle. This is completed by a Cartesian to polar linear interpolation technique. Then some iteration is carried out in the region B using polar coordinates and again a successive over-relaxation (or under-relaxation) procedure. The result of the iterations in the region B is used to update the nodal values along the interface by translating the polar coordinates into Cartesian along the dividing line. The iteration and interpolation procedures are carried out repeatedly until convergence of stream function and vorticity are obtained using suitable convergence criteria as shown below:

|ψ₆ ^(n+1)−ψ₆ ^(n)|<ξ

|ω₆ ^(n'1)−ω₆ ^(n)|<ξ

Where ξ=10⁻⁶ ensures adequate convergence

The data at the nodal points are plotted to form the contours of the stream function depicting the flow distributions or patterns in the heat exchanger. The above interlocking/overlapping technique and the iteration procedure are applied each time the parameters of the non-circular shape for the continuous curvature of an oval shape are varied until the flow distribution or pattern reveals no concentric eddies. At an initial stage flow recirculation or eddies are observed, however, with the variation of the continuous curvature of an oval shape parameters to establish non-axisymmetric flows, eddies finally disappear.

In reference to FIG. 10, when a laser interferometer is utilized to visualize and analyze the flow distribution in the rectangular heat exchanger, an interferogram depicts the corner flow singularities and eddies 41 that are superimposed at the corners. The numerical flow distributions for the rectangular heat exchanger is illustrated with FIG. 9 as the interferogram flow distributions and the numerical flow distributions for the rectangular heat exchanger demonstrate similarities to validate the two different methods. In reference to FIG. 12, when the laser interferometer is utilized to visualize and analyze the flow distribution in the circular heat exchanger, an interferogram depicts the concentric flow eddies or recirculation 42 along with the accompanying non-recoverable energy loss in the form of heat. The numerical flow distributions for the circular heat exchanger is illustrated with FIG. 11 as the interferogram flow distributions and the numerical flow distributions for the circular heat exchanger demonstrate similarities to validate the two different methods. As a result of the corner flow singularities and eddies 41 and the concentric flow eddies or recirculation 42, the rectangular and circular heat exchangers need to provide additional energy to overcome the friction and the energy lost.

In reference to FIG. 14, when the laser interferometer is utilized to visualize and analyze the flow distribution in the heat exchanger coil 1, an interferogram depicts how the present invention is able to overcome the corner flow singularities and the concentric flow eddies with the numerical flow distributions 43. The numerical flow distributions of the present invention is illustrated with FIG. 13, where the numerical flow distributions of the present invention show similarities to the interferogram flow distributions of the present invention to verify the developed stream functions and voracity formulations. Final parameter of the continuous curvature of an oval shape from the numerical simulation is then used in the design and manufacture the heat exchanger coil 1 with the continuous curvature of an oval shape and its non-circular continuous curvature base pan 12 and top cover 13. More specifically, the established parameters are then used in bending a coil slab into a non-circular oval shape profile as well as used in Computer Numerical Control (CNC) operation for the manufacture of the base pan 12 and top cover 13 for the non-circular heat exchanger.

When the present invention is in operation within the condensing unit or outdoor unit, air is drawn through the plurality of cooling fins 6 by the fan and motor assembly.

This operation de-superheats, condenses, cools and sub-cools the superheated refrigerant vapor passing through the plurality of condenser tubes 7. The air having passed through the heat exchanger coil 1 is then discharged back into the environment through the top cover 13. The most unique aspect of the present invention is that the air drawn through the plurality of cooling fins 6 of the heat exchanger coil 1 having continuous curvature of an oval shape do not develop the corner flow singularities and eddies 41 as is the case with rectangular heat exchangers where the corner flow singularities and eddies 41 result in energy dissipation in form of heat. Also the non-circular oval shaped of the heat exchanger coil 1 having continuous curvature induces non-axisymmetric flow to suppress the concentric flow eddies or recirculation 42 that common in circular heat exchangers with the accompanying non-recoverable energy loss in the form of heat. The dissipated or lost energy must be supplied if the air is to be maintained in motion, in the same way, as energy must be provided to overcome the friction. Therefore, without these shortcomings, the continuous curvature of an oval shape of the heat exchanger coil 1 has higher energy efficiency resulting from energy savings due to reduction in fan power, as compared to rectangular or circular heat exchangers; hence an air conditioner unit with the continuous curvature of an oval shape of the heat exchanger coil 1 results in improved EER or SEER in comparison with similar air conditioner with rectangular or circular heat exchangers.

The present invention has been described in detail by making reference to the applications cited. These by no means inclusive as other modifications, variations and arrangements may be envisioned by those skilled in the art of this invention without departing from the spirit and scope of the present invention. For example, alternative construction material, designs of top cover 13 and base pan 12, designs of fan guards, heat exchanger coil 1 designs, blower and motor selections, choice of electrical and electronic components, other ranges of dimensions, choice and means of attachment of components may be considered that differ from those used or described in the present invention.

Although the invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed. 

What is claimed is:
 1. A heat exchanger for a condenser unit which eliminate corner and concentric eddies comprises: a heat exchanger coil; the heat exchanger coil comprises a circular section, a first planar section, a second planar section, and a coil opening; the circular section comprises a first arc edge and a second arc edge; the first planar section and the second planar section each comprise a fixed edge and a free edge; the fixed edge of the first planar section being adjacently connected with the first arc edge; the first planar section being tangentially positioned with the circular section; the fixed edge of the second planar section being adjacently connected with the second arc edge; the second planar section being tangentially positioned with the circular section; and the coil opening being delineated by the free edge of the first planar section and the free edge of the second planar section.
 2. The heat exchanger for a condenser unit which eliminate corner and concentric eddies as claimed in claim 1, wherein first arc edge and the second arc edge are offset from each other along the circular section.
 3. The heat exchanger for a condenser unit which eliminate corner and concentric eddies as claimed in claim 1 comprises: the heat exchanger coil further comprises a plurality of cooling fins, a plurality of condenser tubes, a vapor intake manifold, and a liquid discharge manifold; the plurality of cooling fins being vertically extended from the free edge of the first planar section to the free edge of the second planar section; the plurality of condenser tubes horizontally traversing through the plurality of cooling fins from the free edge of the first planar section to the free edge of the second planar section; the plurality of cooling fins and the plurality of condenser tubes being perpendicularly positioned with each other; and the vapor intake manifold and the liquid discharge manifold being in fluid communication with the plurality of condenser tubes.
 4. The heat exchanger for a condenser unit which eliminate corner and concentric eddies as claimed in claim 1, wherein a path followed by a cross section of the heat exchanger coil is a continuous curvature of an oval shape.
 5. The heat exchanger for a condenser unit which eliminate corner and concentric eddies as claimed in claim 1, wherein an angle between the free edge of the first planar section and the free edge of the second planar section is an acute angle.
 6. The heat exchanger for a condenser unit which eliminate corner and concentric eddies as claimed in claim 5, wherein the acute angle is about 77 degrees;
 7. The heat exchanger for a condenser unit which eliminate corner and concentric eddies as claimed in claim 1 comprises: a base pan; a top cover; a protective grill; a back panel; the base pan being adjacently positioned around a bottom edge of the heat exchanger coil; the top cover being adjacently positioned around a top edge of the heat exchanger coil, opposite of the base pan; the protective grill being concentrically positioned around the heat exchanger coil; the base pan and the top cover being mounted to each other through the protective grill; the back panel being adjacently positioned with the coil opening; the back panel being mounted to the base pan and the top cover; and the base pan, the top cover, and the protective grill being shaped for internal placement of the heat exchanger coil.
 8. The heat exchanger for a condenser unit which eliminate corner and concentric eddies as claimed in claim 1, wherein a chord length between the first arc edge and the second arc edge is greater than a radius of the circular section.
 9. The heat exchanger for a condenser unit which eliminate corner and concentric eddies as claimed in claim 8, wherein a ratio for the chord length and the radius of the circular section is about 1.25 to
 1. 10. The heat exchanger for a condenser unit which eliminate corner and concentric eddies as claimed in claim 8, wherein a ratio for the chord length and a length from the free edge to the fixed edge of the first planar section is about 3.4 to
 1. 11. The heat exchanger for a condenser unit which eliminate corner and concentric eddies as claimed in claim 8, wherein a ratio for the chord length and a length from the free edge to the fixed edge of the second planar section is about 3.4 to
 1. 